In one form of method for clamping tubes or the like which are disposed on a clamping support means either individually or in layers, for example for the purposes of the tubes being cut into sections by means of a suitable cutting device, clamping forces are applied to the tubes on mutually oppositely disposed sides thereof in a direction corresponding to the tube support or mounting plane, the clamping forces being at maximum of such a magnitude that, when only those forces are acting on the tubes or like members, those members do not experience any inadmissible permanent deformation. The tubes or like members are held in position in such a way that one cannot slide up over the other, by means of hold-down forces acting on the tubes or like members transversely with respect to the direction of the above-mentioned support or mounting plane.
In this specification and the claims appended hereto the expression tube or like member, or alternatively, tube-like member, or the plurals thereof, will be used for the sake of brevity and convenience to denote any member to which the present invention is to be applied.
A clamping apparatus which operates on the basis of such a method has clamping jaws which are displaceable relative to each other in the direction of the tube support plane, and also a clamping jaw which is movable transversely with respect to the direction of that plane, being therefore movable in an at least substantially vertical direction towards and away from that plane, in order to hold the tube members down on the support plane. The clamping forces are primarily applied by means of clamping jaws, as referred to above, which thus act in the direction of the support plane. The vertically movable clamping jaw only performs an auxiliary function and, as indicated, essentially acts as a means for holding down the tubes, in order to prevent them from sliding up over each other when subjected to relatively high forces in a direction parallel to the surface on which they are supported, so that the tubes or other members to be cut can be reliably clamped in position.
With the known method however it is not possible, in many circumstances, reliably to prevent the tubes or like members from turning or twisting during the cutting operation, which is performed for example by means of a saw apparatus, particularly when high cutting forces are applied. Twisting or turning of the members during the cutting operation can result in damage to and even destruction of the cutting tools, while also having adverse effects on the quality of the cut at the cut surfaces. It is not possible to remedy such problems by merely increasing the clamping forces as after the clamping operation, the tubes or like members should not suffer from permanent deformation in the region in which they were clamped. That means that the cutting devices usually operate at a considerably lower cutting rate than is technologically and theoretically possible as the turning or twisting moments which are applied to the tubes or like members by virtue of the cutting forces must always be lower than the torque values which are permitted by the clamping forces applied to hold the tubes or like members in position.
In another form of clamping apparatus, the vertically movable clamping jaws have, for each tube-like member to be clamped, a depression or recess of prismatic configuration, which is adapted suitably to the tube-like member. Although higher clamping forces can be applied in a vertical direction by means of such an apparatus, there is the disadvantage that particular clamping jaws are required for different diameters of tube-like members to be clamped, while in addition considerable problems occur when a layer or array of tube-like members is being moved into the clamping region in the machine.
Clamping systems have also been put forward, in which small cylinder means are disposed in the vertically movable clamping jaw, the action of such cylinder means being such that each tube-like member can be individually clamped in position. That arrangement suffers from the disadvantage that it is difficult to arrange the cylinder means in the clamping jaw if tube-like members of different diameters are to be clamped thereby.